1. Field of Invention
The present invention relates to a wiring structure constructed by laminating wiring and circuit elements on a substrate and a method for manufacturing the same. Further, the present invention relates to an electro-optical device provided with such wiring structure.
2. Description of Related Art
A wiring structure of this type can include various circuit elements, such as thin film transistors (TFTs) as switching elements, thin film diodes, capacitors, resistors and the like, and wiring to connect them to each other. Recently, these various elements are frequently constructed three-dimensionally or constructed to form a laminated structure, on a substrate. For example, an arrangement is constructed in such a way that capacitors are arranged on TFTs and wiring electrically connected to the TFTs is formed on the capacitors. This construction permits a high-density wiring structure. As a result, it is possible to achieve miniaturization, narrowness and slimness of the wiring structure and an electronic device including the wiring structure.
More specifically, the wiring structure as described above is constructed, for example, by sandwiching an electro-optical material, such as a liquid crystal and the like, between a pair of substrates, and applied to an electro-optical device such as a liquid crystal device capable of displaying images by transmitting light therethrough. Further, here the image display is realized by changing the state of the electro-optical material to change the transmittance of light and to allow light beams having different gray scales per each of the pixels to be seen.
As such electro-optical device, a device is provided for allowing active matrix driving by including, on one substrate of a pair of substrates, pixel electrodes arranged in a matrix, and scanning lines and data lines provided in such a way to pass between the pixel electrodes, as well as TFTs as pixel switching elements (see, for example, Japanese Unexamined Patent Application Publication No. 2002-122889). In this electro-optical device, the above described various elements are formed on the one side of the substrates. However, if these various elements are deployed over a plane, there is a problem in that a large area is required and the pixel aperture ratio, i.e., the ratio of the overall area of the substrate to an area to transmit light decreases. Thus, if an aforementioned three-dimensional construction of the wiring structure is utilized, such inconvenience can be remarkably reduced. That is, for example, scanning lines having a function as TFTs and gate electrode films of the TFTs is formed on a substrate, data lines are formed on scanning lines, and pixel electrodes are formed on the data lines. As a result, it is possible to improve the pixel aperture ratio by appropriately setting the arrangement of various elements in addition to the miniaturization of the device.